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Yield shear stress dependence on dislocation density and crystal orientation was studied in bulk GaN crystals by nanoindentation examination. The yield shear stress decreased with increasing dislocation density which is estimated by dark spot density in cathodoluminescence, and it decreased with decreasing nanoindentation strain-rate. It reached and coincided at 11.5 GPa for both quasi-static deformed c-plane (0001) and m-plane (10-10) GaN. Taking into account theoretical Peierls–Nabarro stress and yield stress for each slip system, these phenomena were concluded to be an evidence of heterogeneous mechanism associated plastic deformation in GaN crystal. Transmission electron microscopy and molecular dynamics simulation also supported the mechanism with obtained r-plane (-1012) slip line right after plastic deformation, so called pop-in event. The agreement of the experimentally obtained atomic shuffle energy with the calculated twin boundary energy suggested that the nucleation of the local metastable twin boundary along the r-plane concentrated the indentation stress, leading to an r-plane slip. This nanoindentation examination is useful for the characterization of crystalline quality because the wafer mapping of the yield shear stress coincided the photoluminescence mapping which shows increase of emission efficiency due to reduction of non-radiative recombination process by dislocation.

The silicon carbide thin film formation process, completely performed at room temperature, was developed by argon plasma and a chemical vapor deposition using monomethylsilane gas. Time-of-flight secondary ion mass spectrometry showed that siliconcarbon bonds existed in the obtained film, the surface of which could remain specular after the exposure to hydrogen chloride gas at 800 °C. The silicon dangling bonds formed at the silicon surface by the argon plasma are considered to easily accept the monomethylsilane molecules at room temperature to produce the amorphous silicon carbide film.

The Mn deposited clean Si (111) substrates were examined with UHV-TEM and STM that are part of an UHV-TEM/STM integrated characterization system. The Mn deposition with coverages of 5-20 ML followed by annealing at 673 K formed MnSi islands with Moire fringes. They showed metallic character. Subsequent annealing at 873 K dissipated the islands instead of transforming them into MnSi1.7. The re-deposition of Mn and re-annealing at 473 K succeeded to transform MnSi islands into MnSi1.7. The islands had several orientation relationships with substrate Si, and were semiconducting. The growth mechanism of MnSi1.7 is inferred.

180 keV Mn+ ions were implanted in silica glass at doses ranging
from 1×1016 to 2×1017 ions/cm2 at room
temperature. The coordination structure of implanted Mn atoms was studied by
X-ray absorption spectroscopy. It was found that Mn atoms were mainly
coordinated by O atoms in silica glasses as-implanted at doses lower than
5×1016Mn+ions/cm2. The Mn-O bond
distance was 2.07 Å and the coordination number was 4.3 in average. Mn atoms
were mainly coordinated by Mn and O atoms in the glasses as-implanted at
doses higher than 1×1017 Mn+ions/cm2. In
all the glasses, Mn atoms which are coordinated by O atoms were present as
divalent state. After heating at 700 °C in air, Mn atoms were present as
trivalent state and tended to form oxide crystals.

The stress induced transformation in Y2 O3 containing tetra gonal zirconia polycrystals (Y-TZP) by a three-point bending test was studied by Raman microprobe. Transformation zone extends to as large as 100μm in the starting side of the fracture and the transformation zone size becomes smaller in the direction from the starting to the ending side of the fracture. The transformation zone size has no correlation with fracture toughness and Y2O3 content. It is suggested that the transformation plastici y may operate in the initial stage of the fracture. The obtained results have remarkable contrast with the case of the fracture of a pre-indented specimen. The transformation behavior of defect-dominating fracture is also discussed.

The hardening shrinkage of calcium aluminate based ultra-high strength cement becomes nearly zero by using calcium sulphoaluminate compound, and very high bending strength can be obtained by calcinating at 300°-600°C. The starting materials are calcium aluminate, silica fume, calcium sulphoaluminate compound and superplasticizer, and the water-to-power ratio is 0.15–0.25. The main hydration products are C3AH6, AH3, C-S-H and ettringite, forming a densely packed structure, together with a large amount of unreacted cement particles. The hardening shrinkage is remarkably reduced, because of the ettringite formation in the early stage. The bending strength is about 55 MPa when calcined at 600°C. C12A7 is identified by XRD; needle-shaped skeletons of ettringite crystals are observed by SEM. It is suggested that chemically bonding substances are C12A7, amorphous A12O3, and C-S-H in calcined calcium aluminate based DSP with ettringite.

Diffusion experiments of radionuclides in compacted sodium bentonite with a dry density of 1.0 g/cm3 were performed in nitrogen gas atmosphere at 90 °C for 208 d and 375 d. The corrosion experiments of crushed radioactive glass, JSS-A, carried out simultaneously to provide the source of the radionuclides for the diffusion experiments. The normalized elemental mass losses of cesium isotopes and 238Pu were lower than those of boron (ca. 10 g/m2) probably because of the difference of sorption and/or precipitation. The apparent diffusion coefficients of 238Pu, 234U and 125Sb were determined to be 2x 10-14 m2/s, 5x 10-12 m2/s and 2x 10-12 m2/s, respectively. The distribution coefficient of Pu estimated from the diffusion data was of the same order as that from batch sorption experiments. The glass corrosion and the plutonium diffusion were described by the geochemical codes PHREEQE, STRAG4 and GESPER. The calculation results well fitted the observed data.

Highly efficient electron emitting diodes have been fabricated using single-crystalline diamond films epitaxially grown on high-pressure synthesized (100) diamond. These diodes have an internal electrode of a graphitized layer buried below an overgrown diamond layer with a very high resistivity, the structure of which is formed by a combination of heavy ionimplantation and overgrowth techniques. The efficiency of electron emissions from sufficiently hydrogenated p-type diamond surfaces reached 100% in the best case. It is found that H atoms can passivate internal defects created during the ion implantation process. The mechanism of the high efficiency is discussed in relation to electron-hole creations in the thin diamond layer under extremely high electric fields of 107 V/cm.

Thin Pb(Zr, Ti)O3 films were grown on a 8-inch Ir(111)/SiO2/Si substrate by a liquid-source MOCVD system. These films showed dependency of ferroelectric properties on several deposition parameters. PZT single phase was obtained at a substrate temperature of 620°C. The film showed (111) preferred orientation and the Pt/Pb1.16(Zr0.45, Ti0.55)Ox(115nm)/Ir capacitors had excellent ferroelectric properties. The switching charge (Qsw) value (at 2V), saturation voltage (V90) and leakage current density (at 1.5V) were 47.4uC/cm2, 1.7V and 7.5E-8A/cm2 respectively. The capacitor made by using an IrOx top electrode had excellent fatigue-free property.

A secondary ammonium hydrochloride of the peptidic lipid, in which an L-prolyl-L-prolyl-L-proline fragment is coupled with an L-glutamate derivative carrying two long alkyl chains, self-assembles in water to form nanotube structures consisting of a single bilayer wall. Using this lipid nanotube as a template, we carried out the sol—gel transcription to metal oxide nanotubes from aqueous lipid nanotubes without solution catalysts. TEM analysis of the aqueous gel phase, coupled with electron energy-loss spectroscopy (EELS) revealed the presence of a high population of hybrid nanotube architectures with a well-defined lipid/silica interface and thus proved the success of structural transcription from the lipid nanotube template. Besides silica, when changing the lipid nanotube in aqueous solutions to an iced lipid nanotube as a template, we also succeeded in the transcription to transition metal oxide nanotubes (titanium oxide, tantalum oxide, vanadium oxide) was also succeeded. The weakly acidic and mildly catalytic headgroup of the lipid is responsible for the formation of the metal oxide on the surface of the lipid nanotube template.

Enterohaemorrhagic Escherichia coli O157 (O157) is infectious to humans, particularly children, at very low doses and causes not only haemorrhagic colitis but also other serious symptoms. To investigate an association between intestinal bacterial flora and resistance to such infections, we screened faecal samples for the presence of enteric bacteria that are able to suppress the growth of O157. Samples from 303 individuals, 35 children (aged [les ]6 years) and 268 adults (aged 20–59 years), were examined. Colonies with different appearances on sorbitol MacConkey agar medium were screened for the production of bacteriocins inhibitory for O157 in an overlay agar plate assay. O157-inhibiting strains were isolated from 52 individuals. The prevalence of these bacteria tended to rise with age, and was significantly higher among 40- to 59-year-old adults (23/101, 22·8%) than among children (3/35, 8·6%; P<0·05). To test the hypothesis that these bacteriocin-producing strains contribute to resistance against O157 in human adults, we examined faecal samples of 25 healthy O157 carriers. Inhibitory bacteria were more prevalent among the latter (9/25, 36·0%) than among age-matched subjects who did not carry O157 (49/268, 18·3%). It appears, therefore, that inhibitory bacteria in the human gut may play a role in inhibiting propagation of O157 and/or suppressing expression of virulence factors by this pathogen.

Norms for cognitive measures used to assess dementia are scant for
minority groups, in particular for older Japanese Americans. Using the
Consortium to Establish a Registry for Alzheimer's Disease (CERAD)
Neuropsychology Battery, we compared the baseline performance of demented
and nondemented Japanese Americans. Participants came from two harmonized
epidemiological studies of dementia which were examined separately: the
Kame Project, Seattle (350 men and women; 201 nondemented), age 65 and
older; Honolulu-Asia Aging Study (HAAS), Hawaii (418 men; 120
nondemented), age 71 and older. The measures examined were Verbal Fluency;
abbreviated Boston Naming; constructional praxis; and Word List Learning,
Recall, and Recognition. Within each study, the CERAD measures
distinguished between nondemented participants and those with mild
cognitive impairment. Among persons with dementia, average level of
performance decreased as severity of dementia increased. Determinants of
score (age, education, language of administration, stage of dementia)
varied between the two studies. Among Japanese Americans, the CERAD
Neuropsychology Battery distinguished nondemented persons from those with
dementia, but was less consistent in distinguishing levels of severity of
dementia. This battery is useful for comparative epidemiological studies
of dementia in minority populations. (JINS, 2005, 11,
192–201.)

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